Appabatus fob and method of pro



March 5, 1935. o. H. BLACKWOOD ET AL 1,993,316

APPARATUS FOR AND METHOD OF PRODUCING OIL FOG 2 Sheet-Sheet 1 Filed Sept. 14, 1931 m m a E :5 .L 1/ N r L I a g W, $5 ,m F? 50 W March 5, 1935. o. H. BLACKWOOD El AL 1,993,315

APPARATUS FOR AND METHOD OF PRODUCING OIL FOG Filed Sept. 14, 1931 2 Sheets-Sheet 2 as 0J5 Patented Mar. 5, 1935 UNITED STATES APPARATUS FOR AND METHOD OF PRO- DUCING OIL FOG Oswald H. Walter L.

Blackwood, Pittsburgh, Pa., and Shively, East Orange, N.

J., assignors to The Koppers Company of Delaware, a corporation of Delaware Application September 14, 1931, Serial No. 562,716

13 Claims.

Our invention relates to apparatus for and methods of producing oil fog for lubricating gas mains.

Apparatus for successfully producing oil fog for lubricating gas mains has been proposed heretofore and the present invention embodies certain improvements thereover. In some cases, it has been necessary to either atomize or to fully vaporize the oil before it was taken up by a current of gas to be supplied to a gas main. In some forms of apparatus, comparatively large particles of oil have either been carried into the gas main or have formed therein as the result of cooling of the oil vapors and it has been necessary to provide oil drips.

In accordance with the present invention, we provide apparatus in which the gas for carrying the oil vapor is brought into intimate contact with the hot oil and the vaporization of the oil and the collection of vapor by this gas is, therefore, greatly facilitated. This contact is accomplished by causing the gas that collects the vapor to bubble through a body of hot oil before being returned to the current of gas for supplying oil vapor to the gas main.

In order to prevent the carrying of relatively large particles of oil into the gas main or the formation of such particles therein, we have arranged that the vapor-bearing gas is cooled prior to its entrance into the gas main by being united with a stream of cool gas. This arrangement insures that most of the oil vapor will be transformed into an oil fog prior to entering the gas main and that any large droplets or globules of oil will drop out of the gas before the latter enters the gas main.

The detailsof our invention will be described in connection with the accompanying drawings, in which Figure 1 is a plan view of apparatus for practicing the process of our invention;

Fig. 2 is an elevational view of the same, parts being broken away; and

Fig. 3 is .a flow diagram of the gas and oil for producing oil fog in the apparatus of Figs. 1 and 2.

Referring particularly to Figs. 1 and 2 of the drawings, a reservoir 1 supplies oil for vaporization to a tank 2. The reservoir 1 comprises two superposed tanks 3 and 4, the tank 3 operating simply as a reservoir for supplying the tank 4 in which oil is maintained at a constant level by means of a float valve 5. This valve appears in dotted lines in Fig. 1. The tanks 3 and '1 a e connected by means of a pipe 6,

The constant-level tank 4 and the vaporizing tank 2 are connected below the levels of the oil therein by a pipe 7 having a U-bend therein for the purpose of preventing heated oil from the tank 2 from flowing back into the tank 4. The tank 2 and the tank 4 are connected at their respective tops by an equalizing pipe 8, by means of which the fluid pressure in the spaces above the oil in the respective tanks is maintained equal in order that the oil may be maintained therein at the same level regardless of relatively different temperature conditions.

A safety vent 9 is provided in the equalizing pipe. 8. Suitable oil gauges may be provided for the tanks 3 and 4 but they are not shown or described herein as such devices are well known.

Gas for heating the oil in the tank 2 to vaporize it is supplied through a pipe 11 to a burner 12 below the tank 2. The flow of gas to the burner 12 is controlled by a thermostat 13 which regulates the flow of heating gas to maintain uniform temperature of the oil in the tank 2.

Gas for collecting and carrying oil vapor from the heated oil in the tank 2 is supplied by a pipe 14, to which is connected 2. vertical pipe 15 extending approximately to the bottom of the tank 2. The pipe 14 is also connected to a pipe 16 that is connected to a centrifugal device 17, the purpose of which will be later described.-

The pipe 16 is connected adjacent to the centrifugal device 17 to a vertical pipe 18 which is connected with the space above the oil in the tank 2. The centrifugal device is connected at its central top portion to a pipe 19, which conducts gas carrying oil fog to the gas main that is desired to be lubricated.

. In the operation of the apparatus of Figs. 1

r and 2, the tank 3 is supplied with a quantity of oil through a central pipe'22, a vent pipe 23 being opened by a valve 24 for the purpose of filling. The levels of the oilin the respective tanks 4 and 2 are maintained constant by means of the float valve 5 and the equalizing pipe 8. The oil in the tank 2 is heated by the burner 12 to a temperature preferably just below its boiling point to eliminate cracking and carbonization which would occur if the oil were highly heated.

Gas flowing through the pipe 14 divides, part flowing through vertical pipe 15 below the surface of the oil, whereupon it becomes heated by the oil as it bubbles upwardly therethrough and it becomes saturated with oil vapor therefrom. Also, the ascending gas may collect certain of the vapor that occupies the space above the oil.

form an oil fog. Some of the larger particles of oil may drop out of the gas at this point.

The sweep gas and the oil fog therein then flow tangentially into the centrifugal device 17 wherein all of the remaining larger droplets or globules of oil are removed. The gas and oil fog then flow through the pipe 19 which is connected to the gas main to be lubricated.

The flow of gas through the pipes 15 and 16 is regulated by two valves 25 and 26, which deter-.

mine the relative quantities of primary and secondary sweep gas flowing through the respective pipes. Suitably proportional orifices may be substituted for these valves.

The oil removed by the centrifugal device 1'1 is returned by a pipe 27 to the supply pipe '7.

The operation of the apparatus of Figs. 1 and 2 may be more readily understood by reference to the flow diagram ofFig. 3, in which parts corresponding to those of Figs.- 1 and 2 bear similar reference numerals. For convenience, it has been assumed that the gas main 28 which is to be supplied with oil fog supplies gas for fuel for the burner 12 and also for use as sweep gas for collecting oil vapor from the tank 2.

An orifice 29 in the main 28 insures flow through the branch pipes. For convenience, an orifice 30 has been shown in the pipe 16 for controlling the division of gas between the pipes 15 and 16.

It will be noted that the hot primary sweep gas bearing oil vapor from the pipe 18 into the pipe 16 mixes with the cool gas from the pipe 16 and that any oil that is condensed from the mixed gases may collect in a recess in the pipe 16 and drain into the vaporizing tank 2 through the pipe 18. I

It may be desirable in some cases to preheat the primary sweep gas in order to expedite vapori-- zation of the oil by decreasing or eliminating the transfer of sensible heat from the oil to the sweep gas. Also, it may be desirable to, superheat the primary sweep gas after it leaves the vaporization tank in order to completely vaporize any entrained oil and thus increase the amount of fogproduced.

The advantages of the apparatus of our invention are that the primary sweep gas makes intimate contact with the hot oil, increasing the area of exposed oil surface and thus increasing the rate of vaporization. The sweep gas thus collects a greater percentage of oil vapor than would be the case if the gas merely swept over the surface of the hot oil.

The bubling of the gas through the oil agitates the body ofoil and thus prevents local overheating and facilitates heat transfer. This method of operation also permits the oil to vaporize below its boiling point and cracking of the oil. and its carbonization are thereby avoided.

-The arrangement whereby the oil vapor is cooled by mixing with cool sweep gas results in condensing the vapor into fog and the elimination of the larger particles of oil at this period in the operation. The provision of the centrifugal device further insures that no relatively large particles of oil whichwould quickly settle from the gas stream are conveyed to the gas main to be lubricated.

Itwill be obvious to those skilled in the art relating to apparatus of this character that we have provided an arrangement that is simple in structure and efiective in operation to supply oil fog for the lubrication of gas mains.

We claim as our invention:

1. A hot oil fogging apparatus for gas mains comprising: an offtake connection for leading gas from a gas main, an oil heating chamber for heating a body of oil, a primary sweep gas connection for sweeping gas from the offtake connection and bubbling it through the body of oil in the oil heater, an oil-bearing gas off-flow connection from said oil heater, a' secondary sweep gas connection for sweeping gas from the ofitake connection and mixing it with oil-bearing gas from the off-flow connection, means for separating large oil droplets from the so mixed gas mixture, and a connection for conveying gas from the separating means back-into the gas main aforesaid. 7

2. A hot oil fogging apparatus for gas mains comprising: an offtake connection for leading gas from a gas main, an oil heating chamber for heating a body of oil, a primary sweep gas connection for sweeping gas from the offtake connection and bubbling it through the body of oil in the oil heater, an oil-bearing gas off-flow connection from said oil heater, a secondary sweep gas connection for sweeping gas from the offtake connection and mixing it with oil-bearing gas from the off-flow connectionfmeans for soparating large oil droplets from the so mixed gas mixture, a connection for conveying gas from the separating means back to the gas main aforesaid,

- a laterally disposed upper and lower oil reservoir, means for controlling the flow of oil from the upper to the lower reservoir, a connection for feeding oil from the lower oil reservoir to the oil heater and adapted to maintain balancing colunms of oil in the oil heater and the lower reservoir, and a gas pressure line communicably connecting the upper portions of the oil heating chamber and the lower reservoir to maintain the pressures on the oil balancing columns substantially the same.

3. Apparatus for producing oil fog for gas mains which comprises, a gas main, a closed oil heating vessel, means for heating oil in said vessel, means for withdrawing a portion of the stream of gas from the gas main and for introducing the withdrawn portion below the top surface level for the oil in the oil heating vessel to bubble through and collect oil vapor from oil in the vessel, oil vapor condensing means for mixing the oil-vapor bearing gas from the vessel with another stream of relatively 0001 gas to thereby condense the oil vapor into a fog comprising a chamber communicating with said vessel and a conduit for introducing another stream of gas from said main into the chamber,'. and means for conducting fog-laden gas from the oil vapor condensing means back into the gas main.

4. Apparatus for producing oil fog for gas mains which comprises, a gas main, oil heating means for heating a body of oil, by-pass means for withdrawing a portion of the gas in a stream from the gas main, means for bubbling a portion of the gas from the by-pass means through a body of oil in said oil heating means, mixing means for remixing oil bearing gas that may bubble through oil in the oil heating means with another portion of the gas from the by-pass means and that is diverted from entering the oil heating means to cool the oil bearing gas from the oil heating means, and means for reintroducing the mixed gas from the mixing means into the gas main.

5. Apparatus for producing oil fog in gas mains comprising, a gas main, an oil heating vessel, an oif-take for leading a restricted stream of gas from the gas main and bubbling it through the body of oil in the oil heating vessel, an oil hearing gas off-flow connection from said oil heater, a cooler gas ofitake connection for leading a stream of gas from the gas main and mixing it with oil-bearing gas from the off-flow connection, said cooler gas ofitake by-passing the oil heating vessel, and a connection for conveying the mixture of gas from the cooler gas offtake and the oil-bearing off-flow connection back into the gas main.

6. Apparatus for producing oil fog in gas mains comprising, a gas main, an oil heating vessel, an

.ofitake for leading a restricted stream of gas tion, said cooler gas offtake by-passing the oil heating vessel, a centrifugal device for removing larger droplets of oil from the so mixed gas mixture, and a connection for reintroducing the gas from the centrifugal device into the gas main.

7. Apparatus for producing oil fog for gas mains comprising: a gas main; oil heating means for heating a body of oil; a pipe for by-passing a portion of the gas from the gas main and adapted for bubbling the gas through a body of oil in the oil heating means to collect oil vapor from the oil; cooling means for cooling the gas from said pipe and adapted for condensing the oil vapor intofog after the gas has bubbled through the oil and before it can re-enter the main, said cooling means comprising a separating chamber communicating with said oil heating means and a second pipe for conveying gasfrom the main into the separating chamber; and means for conducting the cooled gas from the cooling means back into the gas main.

8. A method of producing oil fog for gas main distribution systems which comprises, heating a bath of oil, withdrawing a portion of the gas from the gas maindistribution system and bubbling it through the heated oil and thereby collecting oil vapor in the gas portion, cooling the gas portion after passing through the oil and 9. The method of producing oil fog for gas distribution mains which comprises, heating an enclosed body of oil to vaporize the same, withdrawing a portion of the gas from the main into which the fog is to be introduced and bubbling the, withdrawn portion through the heated oil and thereby charging it with oil-vapor, mixing the oil bearing issuing gas from the heated oil with a stream of another portion of relatively cool gas withdrawn from the gas distribution main and thereby condensing the oil vapor into a fog, and then conducting the fog-laden gas back into the gas distribution main.

10. The method of producing oil fog ingas distribution mains which comprises, withdrawing a portion of the gas in a stream from a gas distribution main and bubbling the withdrawn stream portion through hot oil and thereby charging the stream portion with oil vapor, di-

verting a portion of the withdrawn stream from entering the hot oil and mixing the relatively cooler diverted portion with the oil-bearing gas stream issuing from the hot oil and thereby condensing the oil vapor into a fog by the mixing, and then reintroducing the oil fog bearing gas from the mixing step back into the gas distribution main.

11. The method of producing oil fog for a gas distribution main which comprises, heating a bath of oil, withdrawing and subsequently preheating a stream of gas from the main and bubbling the preheated stream through the heated oil to collect oil vapor therefrom, withdrawing another stream of gas from the same source and mixing it while relatively cool therefrom with the oil vapor bearing gas issuing from the heated oil and thereby cooling the gas and oil vapor and condensing the latter into oil fog, and then reintroducing the gas and oil fog into the gas distribution main.

12. The method of producing oil fog for a gas distribution main which comprises, heating a bath of oil, withdrawing a stream of gas from the main and bubbling the stream through the heated oil to collect oil vapor therefrom, superheating the oil'vapor'bearing gas issuing from the heated oil, cooling the same to condense the oil vapor into oil fog and then returning the oil fog bearing gas into the gas distribution main.

13. The method of producing oil fog for a gas distribution main which comprises, heating a bath of oil, withdrawing and subsequently preheating a stream of gas from the main and hubbling the preheated stream through the heated oil to collect oil vapor therefrom, superheating the oil vapor bearing gas issuing from the heated oil, cooling the same to condense the oil vapor into oil fog and then returning the oil fog hearing gas into the gas distribution main.

'OSWALD H. BLACKWOOD.

WALTER L. SHIVELY. 

